Conventional rotation rate sensors typically employ double open ended (or H-shaped) tuning forks or single open ended tuning forks for sensing rotation. There are however a number of problems associated with these types of tuning forks.
Conventional open ended tuning forks have a complex structure in order to mechanically isolate them from the housing of the rotation rate sensor. This makes the associated manufacturing process complex and time consuming. Moreover, the complexity of the structure also increases the size of these tuning forks which in turn affects the number of tuning forks which can be produced per wafer of piezoelectric material.
Moreover, conventional open-ended tuning forks are mounted to the housing of the rotation rate sensor in such a way that strains are imparted on the tuning fork as the ambient temperature varies. These strains are due to the mismatch in coefficients of thermal expansion between the housing material and the piezoelectric material of the tuning fork and cause the drive mode and pickup mode vibration frequencies of the tuning fork to vary substantially from the desired frequencies of these modes.
Additionally, conventional open ended tuning forks have numerous vibrational modes below the drive and pickup modes. These vibrational modes can be easily excited by external vibrations and therefore affect the performance of the rotation rate sensor.